Sentence Correction

Transplanting is one of the methods that is commonly used for the seeding of rice in irrigated fields, and is performed either manually or by mechanical transplanting machinery in a variety of spatial configurations.

A - is commonly used for the seeding of rice in irrigated fields, and is performed either manually or by mechanical transplanting machinery in
B - is commonly used for rice seeding in irrigated fields, and is performed either manually or by mechanical transplanting machinery in
C - are commonly used for the seeding of rice in irrigated fields, and is performed either manually or by mechanical transplanting machinery for
D - are commonly used for the seeding of rice in irrigated fields, and is performed either manually or by mechanical transplanting machinery in
E - are commonly used for the seeding of rice in fields that are irrigated, and it is performed either manually or by mechanical transplanting machinery in

A - This answer choice is grammatically incorrect. The relative clause that is commonly used for the seeding of rice in irrigated fields describes the noun that appears immediately before it, namely, methods. Since methods follows one of the and is plural, the verb that follows it also needs to be plural. However, is is singular.

B - Incorrect.

This answer choice is grammatically incorrect and repeats the original Relative Clause error.

C - Incorrect.

Although this answer choice corrects the original Relative Clause error by using the plural verb are, it creates a grammatical error by using the incorrect preposition (for) before the phrase a variety of. The correct idiomatic expression in this case would be in a variety of.

D - Correct.

The relative clause that is commonly used for the seeding of rice in irrigated fields describes the noun that appears immediately before it, namely, methods. This answer choice, therefore, correctly uses the plural verb are.

E - Incorrect.

Although this answer choice corrects the original Relative Clause error by using the plural verb are, it creates Redundancy with the wordy phrase fields that are irrigated. Look for a more concise answer choice.